What role do phospholipids play in biological systems?

Phospholipids are fundamental components of biological membranes, particularly the cell membrane, which serves as a barrier that separates the interior of the cell from the external environment. Their unique structure, consisting of a hydrophilic (water-attracting) "head" and two hydrophobic (water-repelling) "tails," allows them to form a bilayer arrangement.

This bilayer structure is crucial for maintaining the integrity and fluidity of the cell membrane, enabling various functions such as transport of molecules in and out of the cell, cell recognition, and communication with other cells. The amphipathic nature of phospholipids, which have both hydrophilic and hydrophobic parts, is key to the formation of this bilayer, allowing membranes to be selectively permeable and to contain embedded proteins that facilitate numerous cellular processes.